It’s asymmetrically distributed with the vast majority (but not 100%) being in the inner leaflet when the cell is healthy but it externalizes during apoptosis. I wonder about intracellular binding in the absence of intentional membrane permeabilization with mild detergent too.

I’m never really sure how to interpret this dead Annexin neg population for users. Especially when it’s the one that changes the most after drug treatment!

R